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Alexandria, VA, United States

Wolford M.F.,U.S. Navy | Sethian J.D.,U.S. Navy | Myers M.C.,U.S. Navy | Hegeler F.,Commonwealth Technology Inc. | And 2 more authors.
Plasma and Fusion Research | Year: 2013

The United States Naval Research Laboratory is developing an electron beam pumped krypton fluoride laser technology for a direct drive inertial fusion energy power plant. The repetitively pulsed krypton fluoride laser technology being developed meets the fusion energy requirements for laser beam quality, wavelength, and repetition rate. The krypton fluoride laser technology is projected, based on experiments, to meet the requirements for wall plug efficiency and durability. The projected wall plug efficiency based on experiments is greater than 7 percent. The Electra laser using laser triggered gas switches has conducted continuous operation for 90,000 shots at 2.5 Hertz operation (ten hours). The Electra laser has achieved greater than 700 Joules per pulse at 1 and 2.5 Hertz repetition rate. The comparison of krypton fluoride laser performance with krypton fluoride kinetics code shows good agreement for pulse shape and laser yield. Development and operation of a durable pulse power system with solid state switches has achieved a continuous run of 11 million pulses into a resistive load at 10 Hz. © 2013 The Japan Society of Plasma Science and Nuclear Fusion Research.

Wolford M.F.,U.S. Navy | Myers M.C.,U.S. Navy | Hegeler F.,Commonwealth Technology Inc. | Sethian J.D.,U.S. Navy
Physical Chemistry Chemical Physics | Year: 2013

A catalyst free approach for nitrogen oxides (NOx) removal has been developed at the United States Naval Research Laboratory. Our goals were to assess the ability of pulsed electron beam to enhance NOx removal at potential lower capital cost with greater efficiency than other large scale NOx removal methods. Removal efficiency over 95% has been attained for NOx concentrations of 1000 parts per million (ppm), 500 ppm and 200 ppm in nitrogen atmosphere. The NOx concentration dropped from 204 ppm to below 4.8 ppm after 10 shots supplying a total dose of 65 kGy. The resultant chemicals after catalyst free pulsed electron beam processing of NOx are nitrogen and oxygen, same as components of air. Pulsed electron beams in a catalyst free approach remove a larger percentage of NO x than continuous wave electron beam with a catalyst. Catalyst free approach removes issues of handling, collecting, transporting and efficiently distributing chemical byproducts. Pulsed electron beams are as efficient as continuous wave electron beams for small removal percentages and have a significant advantage at higher fractional removal percentages of NO x. Preferential destruction of NO species relative to the removal of NO2 species is observed in the pulsed electron beam reaction chamber. The energy required to remove a kilogram of NOx is nearly the same at pressures of 1.16 atmospheres and 1.02 atmospheres. © 2013 the Owner Societies.

Hegeler F.,Commonwealth Technology Inc. | McGeoch M.W.,PLEX Corporation | Sethian J.D.,U.S. Navy | Sanders H.D.,Applied Pulsed Power Inc. | And 2 more authors.
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2011

A unique all solid-state pulsed power system has been tested at the Naval Research Laboratory that produced 200 kV, 4.5 kA, and 300 ns pulses, continuously for more than 11,500,000 shots into a resistive load at a repetition rate of 10 pps. The Marx has an efficiency of 80% based on calorimetric measurements. This pulser is used to evaluate components and advance solid state designs for a next generation solid-state pulsed power system to drive an electron beam pumped KrF laser system for inertial fusion energy. The solid state pulser, designed and constructed by PLEX LLC, consists of a 12 stage Marx, coupled with a 3rd harmonic stage to sharpen the Marx output waveforms, a main magnetic switch, a compact pulse forming line used as a transit time isolator, and a resistive load. Each Marx stage uses an APP Model S33A compact high voltage switch that consists of 12 series connected thyristors. A life test on individual thyristors showed operation of > 300 M shots at 20 Hz without failure. © 2011 IEEE.

Myers M.C.,U.S. Navy | Hegeler F.,U.S. Navy | Hegeler F.,Commonwealth Technology Inc. | Friedman M.,U.S. Navy | Sethian J.D.,U.S. Navy
PPPS 2001 - Pulsed Power Plasma Science 2001 | Year: 2015

Electra [1] is a large aperture krypton-fluoride laser under development for inertial fusion energy research. The laser will require dual 500 kV, 36 A/cm2, uniform electron beams operating at 5 Hz. Experimental studies have been performed to develop a ∼3000 cm2, cathode capable of generating a 110 kA, 100 ns flat top beam pulse with minimal current density variation (< 10%), fast rise "time (<40 ns), negligible gap closure (<1 cm/μs), and long lifetime (ultimately 108 shots). Time resolved electrical and optical data from the study of various dielectric fiber, carbon, and metal/dielectric cathodes will be discussed. © 2002 IEEE.

Hegeler F.,Code | Hegeler F.,Commonwealth Technology Inc. | Friedman M.,Code | Myers M.C.,Code | And 2 more authors.
PPPS 2001 - Pulsed Power Plasma Science 2001 | Year: 2015

Electra is a repetitively pulsed, electron beam pumped krypton fluoride (KrF) laser that will be used to develop the technology required for inertial fusion energy (IFE). A full scale fusion KrF laser will be pumped with electron beams with cross-sections of 2,500 to 10,000 cm2. Understanding the mechanisms that govern uniform electron beam emission over such large areas is important for the overall system efficiency and durability. This paper presents measurements of the current density along the edge of a large area electron beam. The spatial and temporal current density data is obtained with a Faraday cup array at the anode, and the spatial time-integrated current density is obtained with radiachromic film. MAGIC particle-in-cell (PIC) simulations support the experimental results. Experiments and simulations showed that recessing the cathode minimizes the electric field at the edge and eliminates the edge effect. © 2002 IEEE.

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